Is there any evidence (other than anecdotal) that ferals are becoming more prevalent again? ie, longer term ferals which are not derived from recently escaped swarms from managed stock.
If ferals are becoming more prevalent it implies that mite tolerance is improving.
A fairly recent study (2009) which looked at genetic diversity in Europe found no difference between the genetics of wild colonies in nature reserves and the genetics of managed colonies in the area. The paper did imply that there were more ferals in the US.
Estimating the Density of Honeybee Colonies across Their Natural Range to Fill the Gap in Pollinator Decline Censuses
RODOLFO JAFFé et al.
Restricting the analysis to Europe, however, erased the significant effect of land use, making agricultural landscapes and nature reserves indistinguishable in terms of genetic diversity or colony density.One of the main aims of the Native Irish Honeybee Society Varroa monitoring project is to select and promote varroa tolerance in the honeybee native to Ireland (Apis mellifera mellifera) with a long term view to seeing feral colonies reestablished.Another explanation for the lack of a difference in genetic diversity and colony densities between agricultural landscapes and nature reserves in Europe is that wild honeybee populations may be absent from nature reserves. For instance, we did not detect a higher number of colonies in most European sampling locations compared with those kept by local beekeepers.
At the moment, all I ever see is recently escaped swarms which have taken up residence in a chimney or behind the cladding below the roof of a house.